Abstract:
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Section 305 (b) of the Clean Water Act requires that the U.S. Environmental Protection Agency and the states report to Congress every two years on the status and trends of the surface waters of the United States. For streams and rivers, the state determines designated use for each segment. Based on monitoring data, an assessment is to be made whether the segment supports the designated use. The results are reported in terms of the stream length (km) in each category. Historically, states have not monitored all streams and the 305(b) report has reported only on the length that was assessed. In 2001, the USEPA initiated an effort to improve reporting by developing a Comprehensive Assessment and Listing Methodology. The approach recognizes that states must either conduct a census or a probability survey of all streams within their state. Since 1990, the Environmental Monitoring and Assessment Program (EMAP) has conducted research with USEPA Regions and states to improve survey design approaches for streams. This paper will give an overview of the statistical advances, sampling frame issues, and one potential national survey design approach.
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